Trojan.Downexec.B is a Trojan horse that may download potentially harmful files on to the infected computer. It may also disable security settings of your computer. Follow these steps to remove Trojan.Downexec.B .
1. Follow standard procedure for virus removal
2. Delete these values and subkeys added to registry.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\[16 RANDOM HEXADECIMAL DIGITS]